CLAY LUMPS AND FRIABLE PARTICLES IN AGGREGATE (ASTM-C-142)

Purpose

Clay and fine particles may be present as lumps in natural aggregates. If they are near the surface, these lumps can cause potholes under the influence of traffic. Specifications often limit these particles to a maximum of 1%.

Tools and Materials

  • Weighing equipment accurate to 0.1%
  • Flat pan for spreading test samples in a thin layer
  • sieves called in the test process
  • The drying oven is capable of maintaining a free circulating air temperature of 110°±5°C (230°±9°F).
  • Required Quantity of Test Samples

Testing Process

  1. The test samples shall be prepared in accordance with the ASTM designation: C 117, and after oven drying at 110 ° ± 5 ° C (230 ° ± 9 ° F), shall contain the following quantities: particles to be retained in fine aggregates 1.18 -mm (No. 16) sieve and weighing at least 25 grams. The coarse aggregate sizes and minimum quantities per sample are as follows:
The size of the particles that make up the test sample Minimum weight of test specimen in grams
4.75 to 9.5 mm (No. 4 to 3/8 inch sieve) 1000
9.5 to 19.0 mm (3/8 to .3/4 inch sieve) 2000
19.0 to 37.5 mm (3/4 to 1.5 inch sieve) 3000
Maintained at 37.5 mm (1.5 inch sieve) 5000

Where the test sample contains both fine and coarse aggregates, the material is separated on a 4.75-mm (No. 4) sieve. Fine and coarse fractions are then handled as above.

  1. The weighed samples are spread in a thin layer at the bottom of a container and covered with distilled water for approximately 24 h.
  2. Roll and squeeze individual particles between thumb and forefinger. Try breaking the cuticles but only with the thumb and forefinger. The particles that get degraded in this way are classified as lumps of soil or fine particles.
  3. The detritus is separated from the rest of the sample by a wet sieve in the manner prescribed in the following table.
The size of the particles that make up the test sample Sieve size to remove residue particles
fine aggregate 850 microns (No. 20)
4.75 to 9.5 mm (number 4 to 3/8 inch) 2.36mm (No.8)
9.5 to 19.0 mm (3/8 to 3/4 inch) 4.75 mm (No. 4)
19.0 to 37.5 mm (3/4 to 1.5 in) 4.75 mm (No. 4)
greater than 37.5 mm (1.5 in) 4.75 mm (No. 4)

Shake the sieve during wet sieve operation to assure removal of all small sized particles.

  1. Remove any remaining particles and dry in the oven at 110°±5°C (230°±9°F) to a constant weight. Allow the aggregate to cool and weigh to the nearest 0.1%.

Calculation

p = [(W − R)/W] × 100

P = % of earthen lumps and fine particles


W = Weight of the test sample

R = weight of the particles placed on the specified sieve in the wet sieve

For coarse aggregates, P The size fraction of each sieve will be based on the weighted average of the earthen lumps and fine particles. The coarse aggregate fraction not less than 5% of the total gradation will be tested separately. That coarse aggregate fraction shall be deemed to contain the same percentage of earthen lumps and fine particles as found in the next larger or smaller coarse aggregate fraction.


Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.